One of the most valuable and cherished possessions, for many people, is unquestionably his or her own home, which is reflected by the fact that home improvement beyond the traditional contractor renovation has become a major industry. These home improvements include upgrades in older homes in the form of upgraded electrical service, copper plumbing, and particularly replacement windows. A longstanding reason for window replacement, in addition to improved curb appeal, had been the dramatic improvements in thermal efficiency of the double-paned window arrangement, which had already been incorporated into most new construction.
However, windows to be utilized for either new construction or as replacements have seen further improvement as a result of advances in building technology. Improvements to fenestration products have in part been driven by the need to meet more demanding national standards, and in some locations, local building codes which are even more stringent.
A major factor in devising such strict requirements is the ability of the windows to resist damage caused by storms, where storm damage to homes is typically attributable to the storm surge, flood damage, and wind damage. Damage attributed to hurricane Katrina striking the New Orleans area is estimated to be $81.2 billion dollars, and although much of that amount had been due to the flooding which resulted from the levee breaks, shattered windows from hurricane force winds is a significant contributor. Katrina had reached category five in intensity on the Saffir-Simpson Hurricane Scale, but then dropped to category three intensity once it made landfall, and maintained sustained winds between 110-130 mph. Hurricane Andrew, which in 1992 actually struck the Miami-Dade part of Florida at category five, had been the most costly natural disaster in American history, at roughly $26 billion. Victims of hurricane Andrew reported trying to ride out the storm while listening to the category five winds in excess of 156 mph shatter windows, with the glass being dispersed everywhere.
There were similar reports when hurricane Hugo struck South Carolina in 1989, devastating parts of historic Charleston. While the problem may be more often faced by residents of the southern and gulf states, it is not limited to those geographic areas. The “Great September Gale of 1815” was a category three hurricane that struck Long Island, New York, and broke through the barrier beach to create the inlet that still isolates Long Beach. Also, the New York Hurricane of 1893 directly struck New York City, and the Great New England Hurricane in 1938 killed over 682 people and cause over $4.7 billion in damage (2005 U.S. dollars). On average, a hurricane will make landfall in New England every 10-20 years, with last such case being Hurricane Bob in 1991, which killed ten people and caused 2.8 billion dollars in damage (2005 U.S. dollars). Window damage caused by weather phenomena, although very costly and common because of coastal hurricanes, is also problematic for many parts of the country that experience similar risk of damage during tornado season.
However, many if not most coastal areas now mandate that the windows installed be constructed to be both impact resistant and to satisfy other standards. One such standard includes a requirement that the window be able to withstand, for a set period of time, a certain design pressure (DP). A window with a DP30 rating, which would permit the window to maintain its integrity throughout the sustained winds of a category three hurricane, is rated to a pressure level equivalent to 110 mph wind speed, but is tested structurally at a pressure equivalent to 164 mph. Similarly, a window with a DP40 rating is rated to a pressure level equivalent to a 127 mph wind speed, but is tested at a pressure equivalent to a wind speed of 190 mph, and a DP50 rating requires satisfaction of even higher load requirements. Under high wind loading, it is not uncommon to see a window convex a couple of inches, but when properly designed, the window will regain its original form within the window frame. But this deformation under high wind loads creates another design consideration relating to the hardware.
A typical latch for a slidable sash window is shown by U.S. Pat. No. 4,901,475 to Simpson. A latch bolt is spring-loaded relative to its housing, and capable of movement between a retracted or unlatched position, and an extended or latched position. Only a relatively short throw is needed to retract the latch bolt and permit movement of the sash window.
Similarly, another latch for a tilt window is shown by U.S. Pat. No. 7,171,784 to Eenigenberg. The Eenigenberg latch has the same characteristic short throw to retract the latch bolt within the housing, but additionally offers structure permitting its use as a right-hand or a left-hand latch bolt.
Although the short throw characteristic of these tilt-window latches is very desirable, in terms of convenience to the user, and is satisfactory as far as the utility required for personal security, it is deficient maintaining latch integrity during severe weather conditions. Under the high wind loads experienced during a hurricane, the associated deformation to the window may cause the latch bolt to twist and thus the flat face of the bolt will not remain fully engaged with the jam. Also, the deformation, due to the convexing of the window from the winds, may reduce the amount by which any portion of the latch bolt remains engaged with the jam.
A simple solution to the problem would of course be to use a longer latch bolt, and to design the arrangement to have a longer throw, or travel distance, between the engaged and disengaged positions. However, that approach dilutes the advantageous nature of a quick release latch, where any user is able to easily open the window or rotate the window for cleaning, which generally occurs with far greater frequency than that for which such improved hurricane resistance characteristics are normally needed. This invention discloses a tilt latch capable of maintaining its integrity during high wind loading, while maintaining the convenience and overall utility of a short-throw latch bolt.